1. Field of the Invention
This invention relates to an original reading apparatus for use in a facsimile apparatus, a laser beam printer or other image processing apparatus.
2. Description of the Prior Art
In most original reading apparatuses, the optical system is disposed below the conveyance path of the original.
In FIG. 1 of the accompanying drawings, reference numeral 1 designates an original to be read, reference numeral 2 denotes the feed roller of a separating portion, reference numeral 3 designates the separating friction piece of the separating portion, reference numeral 4 denotes a pair of feed rollers, reference numeral 5 designates a pair of paper discharge rollers, reference numeral 6 denotes an illuminating light source, reference numeral 7 designates a reflecting mirror, reference numeral 8 denotes a lens, reference numeral 9 denotes a solid state image sensor such as CCD, reference numeral 10 designates a printed circuit plate for photoelectric conversion, reference numeral 11 denotes an original carriage, reference numeral 12 designates an original tray, reference numeral 13 denotes a prited circuit plate for control, and reference numeral 14 designates a power source.
The apparatus shown in FIG. 1 is a typical example of the horizontal conveyance of an original and the reading of the information of the lower surface of the original, and such an apparatus has suffered from the disadvantages described below.
Parts forming the optical system are disposed below the conveyance path of the original and therefore, a large space for the optical path must be secured within the apparatus body, and this leads to the difficulty with which the apparatus is made compact.
Since the optical system is disposed at the center of the apparatus, it is difficult to construct the optical system alone as a unit. Also, to endow the apparatus with strength, the structure of the housing must be strengthened and for the optical system, the entire apparatus is made more rigid than necessary. Accordingly, the entire apparatus becomes heavy. Also, the entire apparatus is endowed with rigidity and therefore, it is difficult to separate the optical system and adjust it as a unit and in addition, the production process is limited and it is difficult to make the apparatus inexpensive. Also, where the reflecting mirror 7 faces upward as shown in FIG. 1, the influence of dust adhering to the mirror upon the image is great, and this has led to the necessity of adding a special device for cleaning the mirror or to the increased frequency of the cleaning service, which in turn has led to increased cost.
Also, in the prior art, there is an apparatus in which the optical system is turned back to make the apparatus compact, such as an apparatus shown in FIG. 2 of the accompanying drawings.
In FIG. 2, reference numerals similar to those in FIG. 1 designates similar members. Reference numeral 15 designates a roll of recording paper, reference numeral 16 denotes an idle roller, reference numeral 17 designates a platen roller, reference numeral 18 denotes a recording head such as a thermal head, reference numeral 19 designates a pair of paper discharge rollers, and reference numeral 20 denotes a tray for the recording paper.
In the case of such an apparatus, the original is not conveyed horizontally but is U-turned in the apparatus and therefore, the conveyance path of the original in the apparatus is long and according, the probability of jamming is high. Also, to open the conveying surface for the original, a complicated mechanism is required because the conveying surface for the original lies in the interior of the apparatus body, and this has led to the expensiveness of the apparatus.
Also, in the apparatus of the prior art, the illuminating light source of the optical system which is a consumption part, such as a fluorescent lamp or halogen lamp, is disposed in the interior of the apparatus and therefore, replacement of the light source has usually required some trouble, or where the apparatus is designed to enable the user to replace the light source, there is the necessity of adding a special mechanism, which has led to the complexity and expensiveness of the apparatus.